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From:  Greg Heath <heath@alumni.brown.edu>
Newsgroups: comp.soft-sys.matlab
Subject: Re: PSD and sptool
Date: Sun, 05 Aug 2007 16:17:19 -0700
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On Aug 5, 8:32 am, "Vincenzo Manzoni" <ervin...@tiscali.it> wrote:
> UhmGreg, another question: if I calculate thepowerof this
> signal
>
> Fs = 1024;  % Sample frequency: 1 kHz

UMM ... 1KHz = 1000Hz

> t=0:1/Fs:10;

dt = 1/Fs = 0.0009765625

T = 10 + dt = 10.0009765625

N = T/dt = 10*Fs+1 = 10241

> x = sin(2*pi*10*t); % Sin with frequency = 10 Hz

f0 = 10
T0 = 1/f0 = 0.1

T/T0 = 100.009765625

> with fft following the article which I was cited the post
> before, I obtain an armonic

correction: a harmonic

> at 10 Hz with power 0.5... that is theoretically corret.

Show how you obtained that value.

> If I calculate the power of signal with sptool, I obtain an
> armonic (sic) at 10 Hz with power 1.5625... which change if I
> change NFFT.
>
> I am extremely confused...

There might be a difference in scaling conventions. However,
unless we know exactly what you did and exactly what sptool does,
we can't do anything but guess.

Hope this helps.

Greg